A force feedback apparatus for providing force feedback to an operator using the pressure of a gas jet is proposed (refer to Patent documents 1-3, and Non-patent documents 1 and 2, for example). According to this force feedback apparatus, by combining operation of the operator with virtual reality, in addition to changing, deforming or moving the virtual object displayed in the virtual environment, it becomes also possible to provide force feedback to the operator in synchronization with movement of the virtual object.                [Patent document 1] Japanese Laid-Open Patent Application No. 2001-22499        [Patent document 2] Japanese Laid-Open Patent Application No. 2003-256105        [Patent document 3] Japanese Laid-Open Patent Application No. 2004-157677        [Non-patent document 1] Yuriko Suzuki, “Untethered Force Feedback Interface That Uses Air Jets”, MVE of IEICE, pp. 71-76, July 2003        [Non-patent document 2] Yuriko Suzuki, “Untethered Force Feedback Interface That Uses Air Jets”, SIGGRAPH2004 website, 2004-06, http://www.siggraph.org/ s2004/conference/etech/untethered.php?=conference (searched on 9 Jul. 2004)        [Non-patent document 3] Maggie Orth, “Interface to architecture: integrating technology into the environment in the Brain Opera”, Proceedings of the conference on Designing interactive systems: processes, practices, methods, and techniques, Symposium on Designing Interactive Systems, Amsterdam, the Netherlands, Pages: 266-275, 1997 (ISMN: 0-89719-836-0) ACM Press New York, N.Y., USA        